The present invention relates to a substantially non-stretchable belt made of poly(perfluoro-olefin) filament.
The manufacture of products such as non-wovens, textiles, paper, building materials, filtration products and the like is accomplished by formation of a matt of component materials, which may be but are not necessarily fibers, and interbonding of the materials to produce the product. The matt is typically formed, conveyed or transferred on a belt and it is upon the belt that processing of the matt to the final product is accomplished. This may take the form of forming, drying, bonding, heating, pressing and other common processing steps.
The belt must be capable of supporting the matt, withstanding the conditions of the processing steps, causing substantially few impressions upon the matt surface and be long wearing. Belts used for this purpose can be made of woven wire such as bronze or stainless steel or can be woven from synthetic fibers and filaments such as polyester or bicomponent filaments; see for example U.S. Pat. No. 4,112,982; U.S. Pat. No. 4,086,941; U.S. Pat. No. 4,041,989 and U.S. Pat. No. 3,858,623. These belts exhibit durability characteristics, do not substantially stretch and can be made with a weave which permits passage of an adequate volume of air.
These known belts, however, have several disadvantages. Processing temperatures will be limited by the servicable temperature range of the yarns used to make the belts and this will adversely affect productivity and product parameters. The materials used in the matt making also are able to adhere to the belts, thus contaminating them. This requires that the production lines must be periodically shut down in order to clean the belts. Moreover, some products, such as paper and asphalt contaminate them in such a way that they can not be effectively cleaned. Such belts are also subject to chemical and thermal degradation in the process environment. Finally, they often are effective heat conductors since metal wire, filament or thermal conducting yarn is often used to weave them. Accordingly, they cause significant radiative energy loss during processing operations such as heating, drying and the like.
It is, therefore, an object of the invention to develop a belt which resists contamination by the matt it carries. Another object is the production of a long wearing, durable, substantially nonstretchable belt. A further object is the development of a belt which is not substantially thermally conductive and which can operate at higher service temperatures.